Accusations linking Manchester United goalkeeper David de Gea to a sex scandal have thrown Spain's preparations into turmoil on the eve their Euro 2016 opener.

De Gea is vying with 167-cap veteran and captain Iker Casillas, a hero of Spain's three consecutive major championship triumphs between 2008 and 2012, for a starting place against the Czech Republic in Toulouse on Monday.

De Gea has fiercely denied allegations that he organised a party at which two women were forced to have sex with two other footballers. He called the reports "lies" designed to damage his reputation.

However, the storm, has further complicated coach Vicente del Bosque's decision on whether he will back the on-form De Gea or immensely experienced Casillas.

Contrary to early reports, Del Bosque insisted there had never been any suggestion that De Gea could be sent home.

"We will give him all our support," Del Bosque told Spanish radio station Cadena Cope.

"I have no reason to doubt him."


Big doubts

Casillas made himself a national hero with big saves at crucial moments as Spain won European titles in 2008 and 2012, with the country's maiden World Cup in between in 2010.

However, Del Bosque's loyalty to his captain despite a dramatic dip in form for club and country had previously been widely criticised.

The 35-year-old was a major culprit in Spain's disastrous showing at the 2014 World Cup as the holders bowed out after just two games. Casillas conceded seven goals to the Netherlands and Chile.

A move away from the pressure cooker of Real Madrid after a 19-year career at the Bernabeu to Porto was supposed to bring a new lease of life for Casillas. Instead, a series of high-profile errors led the Portuguese media to christen him "butterfingers" as Porto suffered a trophyless season.

"What he has done is extraordinary. Whoever doesn't recognise that is being malicious," Del Bosque told AFP in a pre-tournament interview.

"All the history he created in his club, what he has done for the national team, I think that is recognised all over the world."

The former Real Madrid boss had appeared irritable in the tournament build-up even before having to face questions over an untimely scandal.

Del Bosque has grown tired of the constant questioning of his decisions since Spain crashed out at the World Cup. The failure has tainted a CV with two Champions Leagues, two La Liga titles, a Euros and the country's sole World Cup.

And the affair will at least ease any backlash should he opt for the experience of Casillas despite De Gea's better form in recent seasons.

De Gea was supposed to be Casillas's successor at Madrid. A long-running transfer saga was frustrated at the last moment when the paper work was submitted seconds after the transfer window closed in August.

Yet, despite that setback, the former Atletico Madrid man still bounced back to win United's Player of the Year for a third consecutive season.

"I am coming off good seasons with Manchester with a lot of confidence. There will always be a debate between the goalkeepers, but we are used to it," said De Gea after starting Spain's final warm-up game in a shock defeat to 137 world-ranked Georgia.

A divisive figure in the Spanish media since clashing with Jose Mourinho at Madrid five years ago, the Georgia defeat started a wave of pro-Casillas propoganda in sections of the Spanish press. The hashtag #CasillasTitular (Casillas starter) has started trending on social networking site Twitter.

No matter who he chooses, the distraction of negative headlines leaves Del Bosque a hostage to fortune should either De Gea or Casillas falter in Spain's bid for a historic 'three-peat.'